>> It seems really you'd want a different matrix for each illuminant, >> and >> in ufraw at least this is decomposed into a WB correction and a >> single >> matrix. That probably works because the off-diagonal elements are >> small. > > That's exactly right.You also need a different matrix For each target > colour temperature, though it's much rarer to change that.
So to sum up: digital cameras are linear devices and (should) have filters close to XYZ, thus a matrix profile is all we need to profile them. But then, I have created profiles (LUT and matrix) for some industrial cameras - RAW image directly from sensor, debayered, linear = gamma 1.0 - and I can only say that I see a very huge difference in image quality between LUT and matrix profiles. Almost all packages for profiling digital cameras create LUT profiles nowadays. Why? As for scanners - which really are digital cameras with one fixed illuminant - almost all profiling packages also create LUT based profiles. Why? Could the main reason be the sensor's filters, perhaps they are not so close to XYZ which makes these devices "perceive" color different than us, in a non-linear fashion (???) - something only a LUT can correct? Mark ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
